powerpc/pci_dn: Add missing of_node_put()

In pci_add_device_node_info(), use of_node_put() to drop the reference
to 'parent' returned by of_get_parent() to keep refcount balance.

Fixes: cca87d30 ("powerpc/pci: Refactor pci_dn")
Co-authored-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Link: https://lore.kernel.org/r/20220701131750.240170-1-windhl@126.com